General Motors may reopen some shuttered factories because it can't produce four of its vehicles fast enough to meet demand, and Chrysler is set to hire more engineers and product development workers.

While both companies still depend on government help, the moves are signs of increased confidence that the U.S. auto market bottomed out last year and will improve in 2010, even without a jolt from a Cash for Clunkers-style program.

GM factories making the Chevrolet Equinox, GMC Terrain and Cadillac SRX, all SUV-like crossovers, and the Buick LaCrosse sedan are at or near capacity, GM's North American president, Mark Reuss, told reporters at the Detroit auto show.

The company will try to squeeze more production out of its existing plants first, Reuss said. He mentioned an idled factory in Spring Hill, Tenn., as a possibility for reopening. GM has closed 14 factories in the past two years.

The head of Chrysler, Sergio Marchionne, said his company does not have enough people to revamp its U.S. product line and soon will start hiring, probably beginning with temporary workers.

"We just don't have the manpower," he said. "We are going to increase heads."

Michael Robinet, an auto industry analyst for the CSM Worldwide consulting firm near Detroit, said Chrysler's former owners cut the engineering and design staffs too far for the company to compete.

Both need to add factory capacity to take advantage of hot-selling models because these days competitors can adapt quickly.

"You have to make hay in the sunshine," he said. "These days, within a year or 18 months you can have competitors with products as good as yours, if not better."

GM and Chrysler both entered and exited bankruptcy in 2009, when Americans bought the fewest cars of any year since 1982. In all, U.S. sales of cars and trucks totaled 10.4 million, roughly 700,000 of them with the help of the government's Cash for Clunkers rebates.

Sales were down 21 percent for last year but up for December, giving the companies hope of gradual improvement this year.

GM Vice Chairman Bob Lutz said GM has lost market share over the years because it has been afraid to raise factory output when it has hot models.

Lutz was the head of product development for Chrysler in the 1990s. He said that company doubled its market share in a few years by immediately cranking up factories to make more of the cars and trucks that were selling well.

He recalled a recent management meeting at GM in which executives suggested holding production steady, even for hot-selling products, for fear that sales would wane and GM would be stuck with unused factories and workers.

"This is why we have never been able to gain share because we won't roll the dice and go with our winners," Lutz remembered saying.

Among the winners now are the Equinox and Terrain, both crossover SUVs equipped with four-cylinder engines that can get up to 32 mpg on the highway. GM had only a 13-day supply of the Equinox and 18 days' worth of Terrains at the end of December.

Besides the Spring Hill plant, GM has also placed its Janesville, Wis., factory on standby.

In Chrysler's case, Marchionne said the timing of hiring more production workers will depend on whether and when the company meets its sales projections. Its former owners, Cerberus Capital Management LP, cut white-collar jobs through layoffs, buyouts and early-retirement offers.

Marchionne also said Chrysler has maintained the $5 billion in cash reserves that it had in November, despite a year in which sales dropped 36 percent.

He pledged Chrysler will not produce too many cars and discount them simply to boost sales numbers. The company, he said, wants to sell at a profitable level but still plans to double U.S. and global sales by 2015.

He said Chrysler's new owner, Fiat Group SpA, which has only been running the company for seven months, is already putting out higher-quality vehicles. The best way to change the public's perception of poor quality is to produce better vehicles, Marchionne said.

"The only thing you can do is shut up, work very hard to get the issues resolved," he said.

At GM, Reuss said if he does his job correctly and restores faith in the GM brands, the company could hire workers again. The company now has about 7,500 workers on layoff.

The Terrain and Equinox are made at a factory in Ingersoll, Ontario, while the LaCrosse is built in Kansas City, Kan. The Ontario factory is working around the clock, and GM has plans to add a third shift to the Kansas City operation.

The SRX is made in Ramos Arizpe, Mexico. GM dealers have reported shortages of all four, and Reuss said he has fielded e-mails from frustrated customers who couldn't get vehicles they ordered.

Reuss also said GM has finished tweaking the Chevrolet Cruze compact car and is ready to begin producing it at the factory in Lordstown, Ohio. Last month he said the production schedule had been stopped while engineers worked out problems with the car.

The Cruze, due out later this year, is a key product for GM as it tries to compete in the growing market for small cars.

Toyota also recently added a second shift of workers to the Ontario plant that produces the RAV4 crossover, said Bob Carter, head of Toyota's U.S. division. Carter said Toyota's Georgetown, Ky., plant, which makes the Camry, hybrid Camry, Avalon sedan and Venza crossover, is at full capacity.

Carter predicted moderate growth in the U.S. market throughout 2010, with sales picking up steam toward the end of the year.

The vital signs are improving for American automakers.General Motors may reopen some shuttered factories because it can't produce four of its vehicles fast enough to meet demand, and Chrysler is set to hire more engineers and product development workers.While both companies...